JP2014049591A - Electron beam pumped light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a structure that the surface of a semiconductor light-emitting element is not charged by an electron beam incident on the semiconductor light-emitting element to cause unstable emission or decreased reliability, in an electron beam pumped light source device including a vacuum container having a light transmission window, a semiconductor light-emitting element arranged so that the surface faces the light transmission window, in the vacuum container, and an electron beam source for irradiating the semiconductor light-emitting element with an electron beam.SOLUTION: An electron beam source 30 is arranged to irradiate the light radiation surface of a semiconductor light-emitting element 20 with an electron beam from the side, the semiconductor light-emitting element 20 includes, on a substrate, a plurality of protrusions extending in a direction orthogonal to the electron beam incident direction, the protrusion has a triangular cross-section, a luminous layer is provided on a taper surface on the electron beam source 30 side where electrons enter, and an antistatic film is provided on a taper surface on the reverse side of the electron beam source 30.

Description

  The present invention relates to an electron beam excitation light source device, and particularly to an electron beam excitation light source device including a semiconductor light emitting element that emits light when excited by an electron beam emitted from an electron beam source.

  Conventionally, as such an electron beam excitation type light source device, it is emitted from an electron beam source as disclosed in Japanese Patent Application Laid-Open No. 09-214027 (Patent Document 1) and Japanese Patent No. 3667188 (Patent Document 2). The electrons are accelerated by an acceleration voltage applied between the electron beam source and the semiconductor light emitting device to form an electron beam, and the semiconductor light emitting device is excited by causing the electron beam to enter the semiconductor light emitting device. The structure which radiates light is adopted.

FIG. 10 shows a schematic configuration of Patent Document 1, which includes an electron beam source 71 and a semiconductor light emitting element 72 in a glass vacuum vessel 70. In the semiconductor light emitting element 72, the electron beam source 71 The electron beam is incident on the upper surface 72 a, and the light emitted in the semiconductor light emitting device 72 is emitted from the incident surface 72 a and emitted outside the vacuum container 70.
Further, FIG. 11 shows a schematic configuration of Patent Document 2, in which an electron beam source 81 and a semiconductor light emitting element 82 are provided in a glass vacuum container 80 so as to face each other, and the semiconductor light emission is performed. In the element 82, one surface 82a facing the electron beam source 81 is irradiated with an electron beam, light is emitted from the surface opposite to the incident surface 82a, and emitted outside the vacuum vessel 80. .

In recent years, such an electron beam excitation type light source device has been expected as a light source device that emits ultraviolet light with a small size and high output, and specifically, a small size device capable of obtaining a high output of several W class is required. ing. For this reason, the electron beam excitation type light source device is desired to have a structure for efficiently extracting light emission from the semiconductor light emitting element. However, it still has challenges.
More specifically, when a semiconductor light emitting element is irradiated with an electron beam, the surface of the semiconductor light emitting element is charged with the electron beam, which causes problems such as unstable light emission and reduced reliability. .

With respect to such a problem, in those disclosed in Patent Document 1 and Patent Document 2, etc., a metal film (that is, a conductive film) is formed on the surface of the semiconductor light-emitting element, and charges are leaked outside the surface of the element. It is going to be solved by adopting a configuration to do. However, in such a case, an undesirable event that a part of the energy of the electron beam is absorbed by the conductive film inevitably occurs, and eventually, another problem that the output cannot be increased occurs. .
In order to compensate for the energy absorption by the conductive film, the electron acceleration voltage must be set high. In this case, discharge in the apparatus and leakage of X-rays to the outside are prevented. Therefore, it is necessary to take measures for this, and the apparatus becomes large, which is contrary to the demand for miniaturization.

  Moreover, in the technique described in Patent Document 1 or Patent Document 2, the metal film is configured as a reflecting mirror for forming a resonator structure, but the effect of this is limited. That is, when using spontaneous emission light, if a conductive film is formed on the surface of a semiconductor light emitting element, light emitted from the element is shielded and cannot be extracted. It is not the fundamental solution to the problem of efficient retrieval.

Japanese Patent Laid-Open No. 09-214027 Japanese Patent No. 3667188

  The problem to be solved by the present invention is to excite an electron beam emitted from an electron beam source by irradiating a semiconductor light emitting device having a light emitting layer formed on a substrate to excite the semiconductor light emitting device. The present invention provides a structure that can suppress charging of a semiconductor light emitting element and emit light with high efficiency in a mold light source.

In order to solve the above problems, in the electron beam excitation light source according to the present invention, the electron beam source is arranged to irradiate an electron beam from the side with respect to the light emitting surface of the semiconductor light emitting element, The semiconductor light emitting device includes a plurality of protrusions extending on a substrate in a direction orthogonal to an electron beam incident direction, the protrusions having a pair of tapered surfaces, and the electron beam source A light emitting layer is provided on the tapered surface on which the electrons on the side are incident, and an antistatic film is provided on the tapered surface opposite to the electron beam source.
Further, the ridge is characterized in that a cross section in a direction orthogonal to the extending direction of the ridge is triangular.
The antistatic film is formed of an aluminum layer.

According to the electron beam excitation light source of the present invention, since the protrusion is formed on the substrate, there is no light confinement due to total reflection in the semiconductor light emitting device, and light is efficiently emitted from the surface of the light emitting layer. .
Moreover, since the cross-sectional shape of the protrusion is triangular, the electron beam can be incident on the entire tapered surface formed on the electron beam source side, and the incident area can be increased.
Furthermore, since the antistatic film is provided on the tapered surface on the side opposite to the electron beam source of the ridge and does not contribute to the electron beam incidence, the semiconductor light emitting device can be charged without obstructing the electron beam incidence. Furthermore, the antistatic film is made of an aluminum layer, so that the light generated in the light-emitting layer is reflected and the reflected light is extracted from the light-emitting layer, contributing to higher output of radiated light. To do.

The side sectional view of the electron beam excitation type light source device of the present invention. FIG. 2 is a plan sectional view of FIG. 1. The top view of the semiconductor light-emitting device in this invention. FIG. 4 is a partial cross-sectional view taken along line AA in FIG. 3. The perspective view of the base material which comprises the semiconductor light-emitting device of this invention. FIG. 6 is a process diagram for forming a semiconductor light emitting element. The fragmentary sectional view (A) and its X section enlarged view (B) of a semiconductor light-emitting device. Sectional drawing of the semiconductor light-emitting device whose protrusion is trapezoid. Explanatory drawing of the electron beam excitation light source device with which the light emission surface inclined. Explanatory drawing of the conventional electron beam excitation type light source device. Explanatory drawing of the other conventional electron beam excitation type light source device.

1 and 2 show the overall configuration of the electron beam excitation light source device 1 of the present invention.
In the figure, the electron beam excitation type light source device 1 includes a vacuum container 10 having a rectangular parallelepiped shape sealed inside in a negative pressure state, and the vacuum container 10 includes a container body 11 having an opening on the upper surface, The light transmitting window 12 is disposed in the opening of the container body 11 and hermetically sealed to the container body 11.
As a material constituting the container main body 11 in the vacuum container 10, an insulator such as glass such as quartz glass and ceramics such as alumina can be used.
Moreover, as a material which comprises the light transmission window 12 in the vacuum vessel 10, the material which can permeate | transmit the light from a semiconductor light-emitting device is used, For example, quartz glass, sapphire, etc. can be used.
Moreover, the pressure inside the vacuum vessel 10 is, for example, 10 ⁻⁴ to 10 ⁻⁶ Pa.
An example of the dimensions of the vacuum container 10 is that the outer dimensions of the container body 11 are 40 mm × 40 mm × 20 mm, the thickness of the container body 11 is 2 mm, the opening of the container body 11 is 36 mm × 36 mm, and the light transmission window 12 The dimensions are 40 mm × 40 mm × 2 mm.

In the vacuum vessel 10, a semiconductor light emitting element 20 is installed on the bottom wall 11 a of the container main body 11, and the upper surface 20 a of the semiconductor light emitting element 20 is disposed so as to be separated from the light transmission window 12 and face the same. The upper surface 20a functions as a light emitting surface.
On the other hand, an electron beam source 30 is fixed to the side wall 11 b of the container body 11. The electron beam source 30 includes a base 31, a support substrate 32 formed on the base 31, an electron emission portion 33 formed on the support substrate 32, and a support substrate 32 and an electron emission portion 33. Is constituted by an extraction electrode 35 disposed forward (electron emission side) with an insulating layer 34 interposed therebetween. An electron beam focusing electrode 36 is disposed in front of the extraction electrode 35 of the electron beam source 30, and the electrons from the electron emission portion 33 are focused and directed to the semiconductor light emitting element 20 as an electron beam.
The electron emission portion 33 is formed by supporting a large number of carbon nanotubes on a support substrate 31 made of a metal material including, for example, iron, nickel, cobalt, or chromium.
The electron beam source 30 having such a configuration is arranged in such a manner that the electron emission portion 32 faces the other opposing side wall of the container body 11 by being attached to the side wall 11 b of the container body 11. With this arrangement structure, the electron beam from the electron beam source 30 has an arrangement relationship in which the electron beam is irradiated from the side to the light emitting surface 20a of the semiconductor light emitting element 20 on the bottom wall 11a.

3 and 4 show the structure of the semiconductor light emitting device 20, and a plurality of protrusions 22, 22 are formed on the substrate 21 so as to extend linearly. As shown in FIG. 4, the protruding portion 22 has a triangular cross-sectional shape in a direction orthogonal to the extending direction, and the surface layer of the two tapered surfaces 22 a and 22 b that are the surfaces of the protruding portion 22 is A light emitting layer 23 is formed along the tapered surface.
An antistatic film 24 is formed on the light emitting layer 23 on one tapered surface 22 b of the protrusion 22.
As a result, the light emitting layer 23 is exposed on one tapered surface 22a of the protruding portion 22, and the antistatic film 24 is formed on the other tapered surface 22b.

  As shown in FIG. 2, the semiconductor light emitting device 20 formed in this way has an extending direction of the protrusion 22 on the upper surface orthogonal to the electron beam from the electron beam source 30 in the vacuum container 10. To be arranged. The tapered surface 22a where the light emitting layer 23 of the protrusion 22 of the semiconductor light emitting device 20 is exposed is disposed at a position facing the electron beam source 30 side, and the tapered surface 22b provided with the antistatic film 24 is opposite thereto. It is arrange | positioned so that it may be located in the side.

FIG. 5 shows a base material 26 constituting such a conductor light emitting element 20, and the base material 26 is, for example, a flat substrate 21 made of, for example, sapphire, and, for example, AlN laminated on the upper surface thereof. And a plurality of buffer layers 25. The buffer layer 25 extends linearly, has a triangular cross section, and has two tapered surfaces 25a and 25b. The buffer layer 25 constitutes the above-described ridge 22, and the two tapered surfaces 25 a and 25 b constitute the tapered surfaces 22 a and 22 b of the ridge 22, respectively.
And as FIG. 4 shows, the light emitting layer 23 is on the taper surfaces 25a and 25b (taper surface 22a, 22b of the protrusion part 22) of the buffer layer 25 (protrusion part 22) in the base material 26 of the said structure. The antistatic film 24 is laminated on the light emitting layer 23 on one of the tapered surfaces 25b (tapered surface 22b).

The semiconductor light emitting element 20 having such a configuration can be formed by, for example, MOCVD (metal organic chemical vapor deposition) as shown in FIG.
Specifically, first, as shown in FIG. 6A, a plurality of linear shapes are formed on the (0001) surface of the substrate 21 made of sapphire by photolithography and reactive ion etching (RIE). The grooves 27 are formed in parallel at a predetermined interval.
Next, as shown in FIG. 6B, a carrier gas composed of hydrogen and nitrogen and a source gas composed of trimethylaluminum and ammonia are formed on one surface of the substrate 21 where a plurality of grooves 27 are formed by MOCVD. By using the vapor phase growth, a buffer layer lower portion 25c having a rectangular parallelepiped cross section made of AlN having a predetermined thickness is formed in each of the bottom portion 27a and the inter-groove portion 21a of the groove 27 of the substrate 21.
Thereafter, as shown in FIG. 6C, by adjusting the vapor phase growth conditions such as the processing temperature, the V / III ratio, and the processing pressure, the buffer layer lower portion 25c is made of AlN and has two tapers. A buffer layer upper portion 25d having a triangular cross section having the surfaces 25a and 25b is formed. Thereby, the buffer layer 25 including the buffer layer lower portion 25c and the buffer layer upper portion 25d is obtained.

On the tapered surfaces 25a and 25b of the buffer layer 25 thus formed on the substrate 21, a carrier gas composed of hydrogen gas and nitrogen gas and a source gas composed of trimethylaluminum, trimethylgallium and ammonia are formed by MOCVD. Single quantum well structure or multiple quantum well structure made of InxAl _y Ga _1-xy N (0 ≦ x <1, 0 <y ≦ 1, x + y ≦ 1) having a predetermined thickness by vapor phase growth The light emitting layer 23 having the structure can be formed, and the semiconductor light emitting element 20 as shown in FIG. 4 can be formed.
Here, when forming a quantum well layer made of InAlGaN, trimethylindium is used as a source gas in addition to the above, and the processing temperature is set lower than when forming a quantum well layer made of AlGaN. Good.

The light emitting layer 23 and the antistatic film 24 will be described in detail below.
As shown in FIGS. 7A and 7B, the tapered surfaces 22a and 22b (tapered surfaces 25a and 25b) of the protrusions 22 (buffer layer 25) of the semiconductor light emitting device 20 obtained as described above are formed. The formed light emitting layer 23 has a single quantum well structure or a multiple quantum well structure, and a single or a plurality of quantum well layers 28 and a single or a plurality of barrier layers 29 are formed by protrusions 22 (buffer layers 25). ) And are alternately stacked in this order. In other words, the quantum well layers 28 and the barrier layers 29 are alternately stacked in this order on the tapered surfaces 22 a and 22 b of the protruding portions 22 in the direction perpendicular to the tapered surfaces. As a result, a quantum well structure is formed, whereby the light emitting layer 23 is formed.
The thickness of each quantum well layer 28 is, for example, 0.5 to 50 nm. The barrier layer 29 has a composition selected such that the forbidden band width is larger than that of the quantum well layer 28. For example, AlN may be used, and each thickness is larger than the well width of the quantum well layer. Specifically, for example, it is 1 to 100 nm.
The period of the quantum well layer 28 constituting the light emitting layer 23 is appropriately set in consideration of the thickness of the whole quantum well layer, the barrier layer and the light emitting layer, the acceleration voltage of the electron beam used, etc. 1-100.

  When a specific numerical example of such a semiconductor light emitting device 20 is given, the substrate 21 is made of sapphire, the thickness is 60 μm, and the groove 27 formed in the substrate 21 has a groove depth of 1 μm, The groove width is 3 μm, and the distance between adjacent grooves 27 is 3 μm. The buffer layer 25 is made of AlN. The thickness of the buffer layer upper portion 25d constituting the ridge 22 (the height of the ridge) is 2.5 μm, and the thickness of the buffer layer lower portion 25c is 25 μm. 600 nm. The light emitting layer 23 is made of an AlGaN layer having a thickness of 500 nm.

An antistatic film 24 is selectively formed on the light emitting layer 23 thus formed.
That is, the antistatic film 24 is formed on the tapered surface 22 b on which the electron beam emitted from the electron beam source 30 is not incident, that is, on the specific tapered surface 22 b positioned on the opposite side of the electron beam source 30. The antistatic film 24 only needs to be formed electrically continuously in the length direction of the ridge 22, and it is not essential that the antistatic film 24 be formed over the entire area of the specific tapered surface 22 b. There may be.
The semiconductor light emitting device 20 includes an electron acceleration power supply (external power supply) for applying an acceleration voltage provided outside the vacuum vessel 10 via a conductive wire (not shown) drawn from the inside of the vacuum vessel 10 to the outside. (Not shown) is electrically connected to the positive electrode side. Similarly to the semiconductor light emitting element 20, the antistatic film 24 is also electrically connected to the conductive wire.
As described above, the antistatic film 24 is laminated on the light emitting layer 23 on the one tapered surface 22b of the protrusion 22 and is connected to the electron acceleration voltage power source, so that it faces the electron beam source 30. Thus, the surface of the light emitting layer 23 on the tapered surface 20a is not excessively charged, and the light emission in the light emitting layer 23 is inhibited from being inhibited.

The antistatic film 24 can be produced, for example, by the following procedure.
1. Method by oblique deposition (sputtering):
After the light emitting layer 23 is entirely formed on the tapered surfaces 22a and 22b of the protrusions 22 of the base member 21, a 100 nm Al aluminum film, for example, is formed on one tapered surface 22b by a vacuum deposition apparatus or a sputtering apparatus. Form.
At this time, when aluminum is vapor-deposited (or sputtered), the semiconductor light emitting element 20 is arranged so that the tapered surface 22b of the protrusion 22 forming the antistatic film 24 is parallel to the vapor deposition (sputtering) source.
As a result, an aluminum film is preferentially formed on one tapered surface 22b, so that an aluminum film as the antistatic film 24 can be obtained relatively easily.
2. Optical lithography method:
A mask having a desired size and shape is produced by photolithography on the semiconductor light emitting element 20 having the linear protrusions 22 formed thereon.
For example, a mask having an opening with a period of 6 μm and a width of 3 μm is formed on the protrusion 22 having a triangular cross section formed at a period of 6 μm, and the tapered surface 22b on the same side of the plurality of protrusions 22 is formed. An antistatic film 24 is formed.
Subsequently, the antistatic film 24 is formed to a predetermined thickness by a vacuum evaporation apparatus or a sputtering apparatus. Specifically, an aluminum film is formed with a thickness of 100 nm.

In the above embodiment, the protrusion 22 has a triangular cross section. However, the present invention is not limited to this, and the cross section may be trapezoidal as shown in FIG.
In FIG. 1, the semiconductor light emitting element 20 is shown as being horizontally disposed in the vacuum vessel 10, but as shown in FIG. 9, the light emitting surface 20a has a lateral electron beam source 30. You may arrange | position so that it may incline a little so that it may face toward.
Furthermore, in the electron beam excitation light source device 1 shown in FIGS. 1 and 2, an example in which one semiconductor light emitting element 20 is arranged with respect to the electron beam source 30 is shown. The semiconductor light emitting element 20 may be disposed, and a plurality of combinations of the electron beam source 30 and the semiconductor light emitting element 20 may be disposed in one container 10.
In these cases, the antistatic films 24 of the plurality of semiconductor light emitting elements 20 are preferably connected to a common potential.

As described above, the electron beam excitation light source of the present invention is arranged such that the electron beam source irradiates the electron beam from the side with respect to the light emitting surface of the semiconductor light emitting device, A plurality of protrusions extending in a direction orthogonal to the electron beam incident direction are provided on the substrate, the protrusions have a pair of tapered surfaces, and electrons on the electron beam source side are incident thereon. Equipped with a light emitting layer on the taper surface and an antistatic film on the taper surface opposite to the electron beam source, there is no confinement of light due to total reflection in the semiconductor light emitting device, and efficiency from the surface of the light emitting layer There is an effect that light is emitted well.
Further, since the protrusion has a pair of tapered surfaces, the electron beam can be incident on the entire tapered surface formed on the electron beam source side, and the incident area can be increased.
Furthermore, since the antistatic film is provided on the tapered surface on the side opposite to the electron beam source of the ridge and does not contribute to the electron beam incidence, the semiconductor light emitting device can be charged without obstructing the electron beam incidence. Can be prevented.
In addition, by constituting this antistatic film with an aluminum layer, the light generated in the light emitting layer is reflected and the reflected light is extracted from the light emitting layer, which contributes to higher output of radiated light. is there.

DESCRIPTION OF SYMBOLS 1 Electron beam excitation type light source 10 Vacuum container 11 Container body 11a Bottom wall 11b Side wall 12 Light transmission window 20 Semiconductor light emitting element 20a Light emission surface (upper surface)
21 Substrate 22 Projection 22a, 22b Tapered surface 23 Light emitting layer 24 Antistatic film 25 Buffer layer 25a, 25b Tapered surface 26 Base material 30 Electron beam source

Claims (3)

A vacuum vessel having a light transmission window;
Inside the vacuum vessel, a semiconductor light emitting element disposed so that the surface faces the light transmission window;
An electron beam source for irradiating the semiconductor light emitting device with an electron beam;
In an electron beam excitation light source device comprising:
The electron beam source is arranged so as to irradiate an electron beam from the side with respect to the light emitting surface of the semiconductor light emitting device,
The semiconductor light emitting device comprises a plurality of protrusions extending on the substrate in a direction orthogonal to the electron beam incident direction,
The protrusion has a pair of tapered surfaces, and includes a light emitting layer on a tapered surface on which electrons on the electron beam source side are incident, and an antistatic film on a tapered surface opposite to the electron beam source. An electron beam excitation type light source device characterized by that.   The electron beam excitation light source device according to claim 1, wherein the protrusion has a triangular cross section in a direction orthogonal to the extending direction of the protrusion. The electron beam excitation type light source device according to claim 1, wherein the antistatic film is formed of an aluminum layer.

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